


When the Sky Collapsed

by Komyxans



Category: Undertale (Video Game)
Genre: (Implications of) dying/death, Angst, Comfort, Feels, Gen, Nighmares, Poorly-placed Puns, Undertale AU I guess, skelebros, things escalate quickly
Language: English
Status: Completed
Published: 2015-12-02
Updated: 2015-12-02
Packaged: 2018-05-04 13:55:12
Rating: Not Rated
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 4,851
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/5336519
Author URL: https://archiveofourown.org/users/Komyxans/pseuds/Komyxans
Summary: <blockquote class="userstuff">
              <p>While the monsters try to free themselves from the Underground, the humans seemed to have other plans. (Terrible AU, I’m sorry)</p>
            </blockquote>





	When the Sky Collapsed

We were so close, too.

The last soul had already passed into our realm and we would utilise it somehow to escape this damned place. When the word spread that a human fell into the Underground, everyone was so relieved. So happy. The wish was finally within reach, so close we could nearly grasp it. We had been smiling all this time, but when we heard, the smiles became more… genuine.

And trust me, I knew all about fixed smiles.

We weren’t sure what would happen to the human. At first, no one seemed to care greatly. We were mere holding on to the fact that we were finally going to be free. We were going to lead this human to Asgore and let him deal with the situation. It would be just like all the other souls we had gathered. No problem.

But that kid… they did not even lay a finger on a Whimsun. Friendships between them and us blossomed rapidly. They laughed at my ‘humerus’ jokes. They even ate my brother’s spaghetti. That takes a lot of ‘friendship’ (read: guts) to do that. 

Just like us monsters at the time, his smile was genuine too. 

It didn’t take long before guilt began to rise in the back of our minds. It was like stabbing the human in their back with the knife which they intentionally discarded to spare us. We knew that they literally were on Hotland’s conveyor belt to be dropped off at Asgore’s palace, ready to be slaughtered like a pig. 

One day, I took the human out for dinner at the resort. Building a connection between myself and the human was not something I generally wanted, seeing what would come next. But I wanted to get rid of this guilt-ridden feeling, so I said things to them that had been against all the wishes and desires of the monsters of the Underground. 

“your journey’s almost over, huh?”

“you must really wanna go home.”

“hey. i know the feeling, buddo. though…”

“maybe sometimes it’s better to take what’s given to you.”

“down here you’ve already got food, drink, friends…”

“is what you have to do…”

“really worth it?”

The human gave me a look that I had seen on his face many times before. However, this time it was slightly different. The expression of determination they were wearing took away all my doubts. They weren’t planning on getting slaughtered. One way or another, they were going to solve this problem without using violence. He wanted to take us to the surface. Every one of us. Alive.

“ah, forget it.”

“I’m rootin’ for ya, kid.”

That was the last time I ever saw the human. I returned to Snowdin to stay with Papyrus and patiently waited until it was all over. Although my brother was aware of the face that we needed the human’s soul to get to the surface, he was too naïve to think of all the things that have been on the minds of most of us. It was nice being around my brother again: I could temporarily stop thinking about the terrible event that was about to happen any time.

It turned out that I did not even have to kill time up until that point. Papyrus was preparing his favourite pasta dish when he received a call. 

“HELLO, THIS IS THE GREAT PAPYRUS SPEAKING! OH HI, UNDYNE!”

I was snoozing on the couch, too lazy to do anything as usual. Papyrus had commanded me multiple times to go to the sentry station in Snowdin, but I said that it was “bone-chilling” outside. He decided it would be best to leave me alone with a groan. 

My brother’s voice woke me up slightly, but not enough to open my eyes. From what I could hear, he was still stirring the pasta sauce while talking on the phone. The two called each other quite frequently, discussing cooking tips or arranging their next appointment. Hearing my brother’s cheery conversations with Undyne always made me smile.

Papyrus continued rambling on the phone: “SO UNDYNE, I HAVE COME UP WITH THE MOST EXQUISITE CHOICE OF INGREDIENTS FOR-“

Suddenly, the house became strangely quiet. The stirring had stopped, too. When I opened my eyes, I saw Papyrus standing on the other side of the room in an obvious search for words. His face showed worry, but mostly confusion. If I had eyebrows, I’d raise them.

“WELL, YES, BUT-“Papyrus stammered, scratching the back of his head. “HE’S HERE. BUT WHY DO YOU WANT-“

Papyrus looked over to me, causing our eyes to meet. While he was still listening to what Undyne had to say, he shrugged. I joined his state of confusion. Did Undyne want to speak to me? Why? She barely ever talked to me.

“I HEARD YOU THE FIRST TIME! I WILL GIVE THE PHONE TO HIM, BUT DON’T EXPECT MUCH. HE HAS BEEN SNOOZING ON THE COUNCH ALL DAY!” My brother darted me a suspicious glance which made grin. Papyrus handed the phone over me, shrugging yet again. I held the phone to my skull, awaiting her words.

“Hey, sleepyhead!” Undyne greeted. I almost heard her smiling, but I also heard it fade slowly after. A long pause made it clear that she was actively trying to think of what she was going to say. But I remained patient. I attempted to ease her up a little without cracking a joke. Just like Papyrus, she was not a fan of my puns either. 

“hey undyne. to what do i owe the pleasure today?”

“It’s no pleasure, really,” She sighed and there was a pause before she spoke up again. “Something’s up. I need you to come here, to the Waterfall. I can’t ask Papyrus, he’d be clueless. And Alphys, she does not… she has no idea what’s going on either.”

I had already gotten off the couch to search for my shoes. “i’ll be there in a second.”

Something was up indeed. The high rock walls and glowing ceiling of the Waterfall crumbled in the distance, the sound of tremors echoing back ominously. This was not the first time that I had seen this happening. There had always been small quakes that made the Underground shudder a bit.

“It’s different now,” Undyne explained while we were observing the rocks with the telescope that I brought along. “This has been going on for days, Sans. And every time, it’s getting worse.”

Alphys was there too, standing close to Undyne with her eyes fixed to the ground. She was playing with her fingers nervously and she obviously felt uncomfortable with the situation. 

“I-I’m no expert at geology but… I don’t think it is an earthquake. T-they usually don’t take this long and this seems t-too consistent to be an earthquake anyway. I could also be a landslide, b-but the tremor has worsened…”

I wasn’t sure what to do with this information. Sure, it was unusual, but did we really need to figure this all out? Soon, the barrier would be broken and we could all escape this place, anyway. 

“it’s probably nothing. landslides happen all the time on mountains, right?”

“B-but Sans… Y-you’re clever. You must have an idea-“ Alphys stammered, apparently surprised by my reaction. 

“Asgore suspected that you knew something about… Well, what’s happening up there,” Undyne interrupted, slightly irritated, “You must have a better answer than that!”

I knew why they came to me to address the issue. Years ago, I used to be researching many different subjects. Some of the research included humans and the surface. It was not extensive by any means, but I had likely looked into it more than the majority of the monsters in the Underground. That did not mean I had an explanation for everything that happened on the surface, though. It could be anything. 

Why couldn’t I even remotely be interested in what might be going on up there? Was it because we were only a few inches away from achieving our goal? Could it be that I was too lazy? I wouldn’t know.

“trust me, it’ll be over before you know it.”

Was it okay…

“But really, Sans. We’ve never had this before. Are you sure-“

…just this once…

“let it slide.”

…to not care at that moment?

We were so close.

\----------

They foolishly trusted my words. I went back to Snowdin shortly after to find my brother cooking up another batch of spaghetti. He still claimed to be puzzled as to why I had to visit Undyne and Alphys. I lied: “it’s nothing bro. it’s just science stuff, which probably doesn’t interest you. we solved it, so don’t worry.” I wasn’t proud of this, but I wanted to avoid unnecessary confrontation as much as possible. Papyrus wouldn’t understand, anyway.

As naïve as my brother is, he did not ask any further questions and we ate pasta and did some puzzles that evening. 

I slept at first, but nightmares haunted me to no end. In my dreams, the human was on his way to Asgore, but he never reached the king. Just before he entered the castle’s gates, the human would turn around with a devilish grin on his face. The child whispered things that I did not comprehend.

“Did you really think this was going to be so easy?”

“We’re not done with you.”

“We’ve changed.” 

I wanted to ask so many questions. What was easy? Who is ‘we’? Who changed? What do you mean? No matter how hard I tried, nothing audible came out of me. The grin, along with the human, would turn into dust. Afterwards, the world would go pitch black. Every time, I woke up with a stabbing pain in my chest. After the third time I shot up in a panicked state like that, Papyrus was at my side. His hand was placed gently on my forehead.

“SANS! ARE YOU OKAY? YOU KEPT TALKING AND SCREAMING IN YOUR SLEEP. I’M WORRIED ABOUT YOUR WELL-BEING.” Papyrus said softly. 

I felt a warm drop of liquid rolling down my cheek and I knew I didn’t feel like lying anymore. When I started shivering, he pulled me into a hug. More tears followed shortly after.

“i don’t know, pap. i just don’t know.”

I slept in Papyrus’ room the nights that followed.

A couple of days later, Alphys was the one who called me up. 

“S-sans, I was hoping you-“

“i already told you i don’t know what’s going on and-“

“Could you please let me finish?” Alphys sounded unusually confident, which caught me off guard. I kept quiet so she would continue. She anxiously asked me if I could go back to the roots of my research. She was certain that the rumbles and quakes were unnatural of origin and she figured that humans might have something to do with it. She even mentioned Asgore again, who also grew increasingly concerned. I wanted to explain yet explain that it was no use, but she insisted. I gave in.

“just don’t be disappointed when you don’t hear what ya wanted to hear.”

“Thanks, Sans.”

I delved into not only my own papers, but also all the literature about humans that the Underground possessed. Not wanting to bother Papyrus with this (he might even get tricked into thinking I was smart), I decided to sit in the ‘Librarby’. Obviously, there were tons of books there that I could use as well.

After an afternoon filled with reading and dozing off, I realised I did not make much progress. Nearly these books were outdated: the handful of books we had were written by monsters who had seen the surface before we were locked away by the humans. Some books had fallen down from the surface since then, but most of them were too damaged to be readable. That left us with very few usable works.

The books spoke of traditions and technology that have visibly changed over time, even to us in the Underground. The items that had washed ashore in the Waterfall recently were clearly different from the rubbish of long ago. The humans have modernised considerably: more convenient tools, niftier gadgets, deadlier weapons… Yeah, we found those too. 

The bitter truth is that we had been down here so long, we didn’t know what even happened on the surface. We pictured the world above as some sort of paradise, but as it turned out, that may very well be a web of lies. I proceeded to tell Alphys my lacklustre findings. She had been staying at Undyne’s place since the tremors started. As I told the Royal Scientist the results, she frowned thoughtfully and as I went on, her face started to show signs of worry.

“T-that makes the whole situation even more unsettling,” she said, her voice hoarse, “if we d-don’t even have a single clue what might be going on up there. Or why.”

“yeah. let’s just hope the kid hurries,” I said, but I regretted it nearly immediately. We all worked so hard to take ourselves to freedom, but the more I thought about it, the worse the idea became. Nevertheless, I dropped the subject, lazy as I was. 

To deal with the suspense of the current events, the ‘group’ came together to meet up more frequently. They were mostly fun afternoons, and seeing Papyrus so excited about every meeting lifted everyone’s spirits considerably. 

We cooked (well, actually, Papyrus and Undyne were the ones who did the cooking. Alphys and I are wouldn’t mind cheap processed food, unlike them), we played games, watched a ‘ton’ of Mettaton movies and eventually, the others were working on Papyrus’ puzzles while I slowly drifted away from reality on the couch. 

It occurred to me that the rumbling stopped that day. Everyone seemed to be relieved. However, after the constant noise, the silence was unnerving to me. Why did I feel so uncomfortable about a supposedly comforting thought?

It took a while for me to fall asleep that afternoon.

\----------

Nightmares were brutally interrupted by severe tremors and screeching of a drill. I found myself paralysed with fear while my mind was still in the process of waking up and trying to figure out what was going on. One by one, cracks appeared on the walls around me and clouds of dust filled the room. The fear was quickly replaced by panic. I turned my head to the table where everyone was sitting before I fell asleep. Nothing but a huge piece of concrete that dropped from the ceiling.

I just woke from a nightmare only to wake up in hell.

“Sans!” I heard a familiar voice shouting at me. Alphys was standing in the doorway with an injured Undyne around her shoulder. It seemed as if her back and left leg were cut open, but I had no time to examine her thoroughly. 

“W-watch out!” Alphys shrieked. From the corner of my eye socket I saw another part of the ceiling breaking and it came falling right at me at full force. Reflexes kicked in: with a little help from my magic, I was barely able to roll away before being squashed. 

Alphys gasped, but once she saw I saw alright, she shouted over the echoing sounds of shifting boulders: “G-get over here, quick!”

I tried to make my way to her. While I was stepping around cautiously, I realised that Papyrus was not here. Alphys saw that I had moved away from the most dangerous area and was about to exit the house. But…

Papyrus could still be inside.

“where’s papyrus?” I asked the reptilian monster. She didn’t turn to look at me.

“He already went back to Snowdin before it s-started. He w-wanted to do some cleaning, he said. I t-think he left about thirty minutes ago. I don’t k-know…” she stammered, clearly unsure about what she wanted to say. 

From that point on, I didn’t hear much anymore. Or saw anything at all. Magic was flowing freely. 

“Go to the barrier.”

“B-but Sans, y-your eye--“

I had already left before she could finish her sentence. I traced the path that Papyrus and I usually walked from our house to Undyne’s. I dared to look up once or twice, but that decision was regretted shortly afterwards. Large pieces of luminous rocks cracked from the ceiling and dropped down in large numbers. With the added dust, it had a certain beauty to it. If only the stone roof was not attempting to murder us. 

The high-pitched buzzing of the mechanical drill numbed my thoughts, making it hard to focus. Where the hell would Papyrus be? I had been sprinting, virtually following my brother’s footsteps but I had grown tired quickly. My regular day consisted of sleeping and hanging around all day. Exercising was not part of that schedule. I forced my body to keep going, pumping more magic into it. It wasn’t the best idea; I could pass out any second, but I had to keep going.

“pap! bro, are you here? please respond,” I called out, but only the drill answered me. 

While I was running and searching, I recalled parts of the nightmares that had been haunting me. The things the human child whispered to me… 

Did you really think this was going to be so easy? 

We’ve changed.

I realised that this dialogue was not between me and the child, but between monsters and humans. Without truly being aware of it, the humans had not only developed their technology: they had also altered their way of thinking. Their entire lifestyle. They were drilling into the mountain, demolishing all the walls of the Underground. They’d manually break the barriers between the two races, but that didn’t matter once we’re all covered in stone and dust. 

Why did they do this? Were the humans out for revenge? Were they going to avenge their ancestors for what we did to them? Or were they just power-hungry? Was there some important ore in the mountain that they could use to upgrade their fancy technology? I didn’t think we’d be around long enough to find out.

As I avoided some of the falling pebbles, I erased that thought from my mind. No, I said to myself, I’m going to get me and Papyrus out of here.

Approaching the exit of the Waterfall, I looked over the ravishing damage: large chunks of rock had fallen heavily here, obscuring my view considerably. It seemed as if there was still a narrow passageway that led to Snowdin, but everywhere else, the ground was blanketed in even more dust and boulders. 

Above me, another rock came falling down at full speed. I managed to jump away the last second, but I felt that something had fallen out of my pocket. It clattered audibly on the surface right next to me. I couldn’t remember what I put in there that would make such a sound, so I peered over to my side to find a slightly damaged cell phone.

Of course.

That cell phone was handed to me by Alphys, who didn’t want to bother Papyrus each time she or Undyne wanted to give me an update about the earthquakes. Papyrus’s number had to be in there too. I felt extremely stupid for not trying to call him before.

I picked it up swiftly but cautiously, hoping not to break the device any more. The hinge had a crack in it on one side, but the device booted up normally. I exhaled a sigh of relief. 

Finding Papyrus’ number was a matter of seconds. Now I had to hope for signal, as there was a good chance that some rock destroyed the mast too. 

I heard a couple of beeps, meaning the signal hadn’t disappeared yet. Papyrus didn’t pick up the phone, though. 

“fuck,” I mumbled to myself, panic rising to my throat. I tried again, hoping that he just didn’t hear it the first time. No response. I tried again. Nothing. 

“fuck, papyrus, come on-“

“SANS?”

The drilling noises slowly faded into the distance when I heard my brother’s voice through the speaker. He’s alive. 

“pap,” I breathed. I wanted to ask and say so many things. Let’s just starts with the basics: “where are you?”

“I DON’T KNOW, I JUST WOKE UP,” Papyrus said, his voice slower than his usually overenthusiastic self. There was a pause before he continued. “THE LAST THING I CAN REMEMBER IS THAT THE SKY WAS COLLAPSING.”

“just tell me where you are, bro.”

“I HAVE TO ASSUME THAT I AM STUCK, SANS. THERE ARE ROCKS ALL AROUND ME. “

Oh no.

“I AM KIND OF CRAMPED IN HERE. THE BOULDERS ARE TOO HEAVY TO MOVE.” Papyrus said. Before I had the chance to answer, he continued: “WHERE ARE THE OTHERS? ARE UNDYNE AND ALPHYS SAFE?”

It was not until this moment that I realised how much I had put everyone in danger. I said everything was fine, and because of that, everyone was… Papyrus was… “they are okay,” I said. My voice was shaking. “they’ve gone up to the barrier.” I paused before changing the subject. “where were you before you passed out?”

“I REMEMBER I WAS CLOSE TO SNOWDIN! DO YOU HAVE ANY IDEA WHAT IS HAPPENING?”

“pap, i…”I began, but stopped myself. Telling the truth might cause him to panic, which I didn’t want to happen. So I figured I would just get to the point. “we need to get to the barrier. try to make some noise so i can find you.”

Without warning, Papyrus started shouting into his phone. I didn’t exactly mean it like that, but I guessed it didn’t matter. I muted my phone and moved to several piles of stone rubble. After a short while, over the nearly deafening sounds of the drill, I heard sounds coming from an insanely big pile of boulders towering high above me. Part of the wall had fallen as one big avalanche, unlike most other areas where the rocks fell in a more random and periodic manner. As I moved closer, the cries became a little clearer and soon, they became recognisable as Papyrus’ cries. Filled with terror, I ran up to the enormous pile. I unmuted my phone. As predicted, Papyrus was still screaming through the speaker.

“papyrus, i think i found you. hang on.”

“I BELIEVE I CAN HEAR YOU TOO!”

The first rocks were easy to move out of the way. However, they seemed to exponentially increase in size. Beads of sweat rolled over my skull as I attempted to roll away the larger ones. Most of them wouldn’t even budge. Magic was no use either. I was extremely exhausted from the running and lifting, so nearly all power had escaped my body already. Involuntarily, I dropped to my knees. Feelings of guilt washed over me. Why didn’t I listen to Undyne and Alphys back then? Why did I waste too much magic on my way here? Why had I been lying to Papyrus?...

“I DON’T THINK YOU ARE ABLE TO MOVE THE ROCKS, SANS. I COULDN’T EITHER.” Papyrus said quieter than before. I nodded, even though he wouldn’t be able to see it anyway.

“yeah.” I was at a loss for words. 

“MAYBE YOU CAN STILL MAKE IT TO THE BARRIER IF YOU HURRY!” Papyrus exclaimed, his voice filled with hope. “YOU CAN-”

“no.” I said. Tears rose up to my eyes. There was no way in hell that I would leave him alone. “you know I can’t leave you here to die.” It’s time that I started speaking the truth. It was quiet on the line for a couple of minutes. Papyrus’ breathing gradually became heavier.

“are you okay, bro?” I asked. Before I received an answer, I heard more cracking above and behind me. When I turned around, I saw rocks in nearly unbelievable sizes letting go of the ceiling. My only option was to go through the narrow passage to Snowdin, which served as a shelter now. When I managed to enter the narrow path, a boulder fell down behind me. I couldn’t go back to Papyrus or the barrier. 

Shit.

I heard the faint sound of Papyrus talking on the phone. With trembling fingers, I brought the device back up to the side of my skull again. 

“SANS! I H- DI- ROCKS F- … LESS S-“

The signal has worsened dramatically, making it even impossible to make out what my brother was trying to say. I didn’t dare to hang up, though. I considered my options before I arrived at a solution. A radical, terrifying solution.

“hey bro, i’m still okay.” I said. Papyrus replied, but I couldn’t make anything comprehensible out of it. I followed my way through the passage, having to duck and crawl regularly in order to progress. 

“the following will rock your mind. get it?” I told him, grinning, although I wasn’t enjoying it myself, “you probably won’t even get mad about it now because ya couldn’t hear it, i guess. it doesn’t really matter since i don’t think i would’ve told you the plan anyways. i doubt you’d understand…”

I heard silence between the static. Did he hear what I said? Or did anything happen to him? I tried not to think about it too much.

“anyway, i’m almost back in snowdin. luckily our house is on the edge of town, heh.” I said. I could finally peek over the hill to find Snowdin: it was been completely destroyed and abandoned. The majority of the buildings had been crushed completely. Seeing our hometown like this filled me with sorrow. 

“i’m gonna check if it’s still standing.” I explained. Again, no reply was given. Papyrus had been quiet for a long time now. Retaining my sanity has become problematic. “pap, i really need you to keep talking to me. please, just let me know you’re not…”

“I CAN’T H- … STA- … LO- … SO CA-…“ Papyrus spoke, his voice much lower and weaker than usual. To be honest, I had never heard Papyrus like this. Even though I was extremely relieved to hear him speak again, this wasn’t a good sign. 

“the signal’s still bad bro. but please, keep talking while I...” I said, but I paused when I saw our house. The front, where the living room and kitchen were located, had been smashed to bits. Fortunately, Papyrus had not been home yet when this happened. “…will try to get us out of here. hang on, bro.”

I rushed to the back of the house. It had been damaged, but not nearly as bad as the other side of the house. The door there was still intact, so I needed to grab my keys. It proved to be quite a challenge with only one hand that was shaking as well. After finally succeeding, I ran inside to the very end of the room. The machine was still there, completely unharmed and covered with a large blue cloth. 

My wish was to never see that awful thing again, but my choices were obviously limited. 

I pulled off the cloth and rapidly started to get the machine to work. I held the phone with my shoulder since I needed both my hands to connect the wires properly. I heard an increasing amount of rumbles and they were getting closer as well. I had to hurry. 

“papyrus?” I said while attempting another boot-up. It failed. Ragged breathing.

“come on pap, keep talking to me. i don’t care about what. you can explain your newest puzzle for example. i don’t mind, but say something. anything.” I said with a desperate, trembling voice. I didn’t even recognise it myself. 

“…LOVE –OU.”

Uncontrollable tears ran down my checks as I did another attempt to turn on the machine. 

“i love you t-too, pap. give me a couple of minutes. please hang on until then, okay?”

Again, he said something that I couldn’t understand, but at least he said something. While trying to turn on the device yet again, the power failed for a second before turning back on again. The collapse must have taken a heavy toll on the CORE, too. Hopefully the power was going to last long enough. 

After what may have been the tenth attempt, the machine finally remained turned on, ready to be used. I wasn’t happy for long because the earth shook violently by continuously falling rocks. One hit the house again. 

This is the end.

“papyrus?”

The line was dead.

I went inside. It had been a long time since I used this machine, so I had to mess around with the settings. The information I entered was literally a shot in the dark, but I had no more time to edit it. The power failed more frequently and I heard a massive boulder falling through the roof of the back room. Its tremors nearly made me fall over. 

“i’m sorry,” I whispered laying my finger gently on the ‘execute’ button, but not pressing it, “i’m coming for you, pap.”

I pushed down and everything went white before turning black.

**Author's Note:**

> This idea had been on my mind for a very long time, but I only got around to write it now. 
> 
> It always bothered me that the monsters just assumed that they would get along with the humans. Looking at our current society, we’d probably bomb them for no particular reason. Yep, we’re terrible. 
> 
> First fanfic I’ve written in over five years! English is not my native language, so I'm sorry if anything sounded awkward. Comments (and Kudos?) are greatly appreciated! Cheers!


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